I have mixed three Voronoi Textures to get the bumping of the material (see turquoise frame). I have used a Value node and two Math node with the Multiply option to centralize the scaling my textures. If the value of the Value node is changed, all the textures changes in the same proportion. By plugging these textures in Bump nodes and chaining them I get a kind of eroded surface.

Regarding the purple frame, I have used two of the Voronoi textures to find the holes on the surface and set a different color for them. They are the white spots of the coral.

The red frame is a simple material: a mixing of a diffuse and glossy shaders with fresnel factor. After that I have added it a Translucent shader. So the material absorbs some light.El recuadro rojo es un material simple: una mezcla de shaders difuso y de brillo, con un factor de mezcla fresnel. Después de eso le he añadido un shader translúcido. Así el material absorbe algo de luz.This is an abstract render which I did with this material (HD version here):